When the diagram is exported to PDF with the Text Rendering Policy set to Plain Text or Plain Text with embedded Fonts, any label with the Configuration property set to "Cropping" is not exported as readable/searchable text.
If the label Configuration is set to "Standard", the text in the exported pdf is selectable/searchable.
But for any label where we need text-wrapping, we have to set its Configuration to cropping. And then the text will not be exported properly to pdf! :(